HARRISBURG, Pa. — The “conspiracy of silence” that protected Jerry Sandusky extended all the way to the top at Penn State, prosecutors said Thursday as they charged former university President Graham Spanier with hushing up child sexual abuse allegations against the former assistant football coach.

Prosecutors also added counts against two of Spanier’s former underlings, Tim Curley and Gary Schultz, who were already charged with lying to a grand jury.

“This was not a mistake by these men. This was not an oversight. It was not misjudgment on their part,” said state Attorney General Linda Kelly. “This was a conspiracy of silence by top officials to actively conceal the truth.”

Spanier’s lawyers issued a statement that asserted his innocence and described the new charges as an attempt by Gov. Tom Corbett to divert attention from the three-year investigation that began under his watch as attorney general.

“These charges are the work of a vindictive and politically motivated governor working through an unelected attorney general ... whom he appointed to do his bidding,” the four defense lawyers wrote.

Corbett spokesman Kevin Harley said the defense statement “sounds like the ranting of a desperate man who just got indicted.”

Curley’s lawyer Caroline Roberto said he was innocent of all charges, as he has asserted in the past. She said the new documents were being reviewed and would have a more comprehensive comment later. Schultz also has maintained his innocence; his lawyer did not return a message seeking comment.

At a Capitol news conference, Kelly said all three men “knowingly testified falsely and failed to provide important information and evidence.”

Spanier was charged with perjury, obstruction, endangering the welfare of children, failure to properly report suspected abuse and conspiracy. Curley and Schultz face new charges of endangering the welfare of children, obstruction and conspiracy.

The charges were filed with a suburban Harrisburg district judge, whose office said Curley and Schultz were expected to be arraigned Friday afternoon and Spanier tentatively scheduled to appear Wednesday. They came nearly a year to the day that Sandusky was arrested.

Sandusky, who spent decades on the Penn State staff and was defensive coordinator during two national championship seasons, was convicted in June of sexually abusing 10 boys over 15 years. He has maintained he is innocent and was transferred to a maximum security prison on Wednesday, where he is serving a 30- to 60-year sentence.